1. Field of the Invention
The present invention is directed to screens for shale shakers and vibratory separators, and, in certain particular aspects, to screens with aligned wires.
2. Description of Related Art
Vibratory separators are used in a wide variety of industries to separate materials such as liquids from solids or solids from solids. In the oil and gas industries, shale shakers use screens to treat drilling fluid contaminated with undesirable solids. Typically such apparatuses have a basket, deck, or other screen holding or mounting structure mounted in or over a receiving receptacle or tank and vibrating apparatus for vibrating one or more screens. Material to be treated is introduced to the screen(s) either by flowing it directly onto the screen(s) or by flowing it into a container, tank, or “possum belly” from which it then flows to the screen(s).
In a variety of prior art screens, screen mesh or screen cloth as manufactured has a plurality of initially substantially square or rectangular openings defined by intersecting wires of the screen; i.e., as made a first plurality of substantially parallel wires extending in one general direction are perpendicular to a second plurality of substantially parallel wires, all the wires defining square or rectangular openings. In placing one such screen mesh or cloth on top of another, it can happen accidentally that wires of one layer are aligned with wires of another layer; but no effort is made to insure that a large portion, a majority, or substantially all wires of one layer are aligned with wires of another layer. In many actual uses, misalignment of wires occurs, resulting in the deformation of desired openings between wires and, therefore, in reduced screen effectiveness, reduced efficiency, and premature screen failure.
There has long been a need, recognized by the present inventors, for effective screens for shakers and separators. There has long been a need, recognized by the present inventors, for such screens with a substantial portion of aligned wires.